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/* @file
* Tree view that uses the model's moveRows(), if implemented, to
* support internalMoves. The model must also have Qt::MoveAction
* among the supportedDropActions, and its item flags must allow drag
* and drop.
*
* The normal Qt Drag and Drop approach for moves involves inserting a
* new row and removing the original row. That has greater generality,
* but works poorly for views like the I/O Graphs Dialog where a newly
* inserted row would require an expensive retap.
*
* Copyright 2024 John Thacker <johnthacker@gmail.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "rowmove_tree_view.h"
#include <QDropEvent>
RowMoveTreeView::RowMoveTreeView(QWidget *parent) : TabnavTreeView(parent)
{
// QTreeViews default to row selection.
// setSelectionMode(QAbstractItemView::ContiguousSelection);
// ContiguousSelection works, but we probably want to make sure
// that the models we use this for can handle removing multiple
// rows (and that the dialogs support doing that.)
setDropIndicatorShown(true);
// We could override dragMoveEvent to have the dropIndicator cover
// the entire row.
setDragDropMode(QAbstractItemView::InternalMove);
// Classes can change this if they also support other drag and drop
// modes.
}
void RowMoveTreeView::dropEvent(QDropEvent *event)
{
if (event->source() == this && (event->possibleActions() & Qt::MoveAction) && !event->isAccepted()) {
const QModelIndexList sourceIndices = selectionModel()->selectedRows();
if (sourceIndices.empty()) {
TabnavTreeView::dropEvent(event);
return;
}
#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
QModelIndex destIndex = indexAt(event->position().toPoint());
#else
QModelIndex destIndex = indexAt(event->pos());
#endif
if (!destIndex.isValid() || destIndex.row() == -1) {
destIndex = model()->index(model()->rowCount() - 1, 0);
}
// dropIndicatorPosition() can be used to determine if we're slightly
// above the item, slightly below the item, on top, or elsewhere in
// the viewPort. We will just use the row number, table-like.
// Note that if we setDragDropOverwriteMode(true) then there wouldn't
// be graphical hints in between rows, but that could cause issues
// if we added non internalMove handling; overriding dragMoveEvent
// could also change it.
const auto minmaxIndex = std::minmax_element(sourceIndices.begin(), sourceIndices.end(),
[](const QModelIndex &a, const QModelIndex &b)
{ return a.row() < b.row(); }
);
// Only allow a contiguous selection. (This check is unnecessary
// if the selectionMode is SingleSelection or ContiguousSelection.)
// We could handle multiple ranges with multiple moveRows() calls
// and QPersistentModelIndexes in place of the QModelIndexes, but
// it gets a little confusing, especially if some indices are above
// the target row and some are below (the default behavior would be
// to move all the indices above to immediately below, and vice versa.)
// Microsoft Excel doesn't allow row moves unless the selected
// rows are contiguous, and has an alert.
//
// Note that selectionModel()->selection()->size() is *not*
// guaranteed to be the minimal merged number of possible ranges
// if the selection order was unusual, so we can't just use it.
if ((minmaxIndex.second->row() - minmaxIndex.first->row() + 1) == sourceIndices.size()) {
if (model()->moveRows(QModelIndex(), minmaxIndex.first->row(), static_cast<int>(sourceIndices.size()), QModelIndex(), destIndex.row())) {
// Prevent QAbstractItemView from removing the sourceIndices
// There's an element in the private class (dropEventMoved)
// that QTreeWidget and QTableWidget use via the d-pointer,
// but as long as the action is no longer a MoveAction when
// it returns it won't get removed.
event->setDropAction(Qt::IgnoreAction);
event->accept();
}
}
}
TabnavTreeView::dropEvent(event);
}
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